Inductive element for providing mri compatibility in an implantable medical device lead

ABSTRACT

A system includes a medical device lead including a connector at a proximal end of the lead, a conductor electrically connected to the connector at a proximal end of the conductor, and at least one electrode coupled to a distal end of the conductor. The system further includes a device securable to the proximal end of the lead including an inductive element. The device includes a port configured to receive the connector and position the inductive element around at least a portion of the connector.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of Provisional Application No.61/715,627, filed Oct. 18, 2012, which is incorporated herein byreference in its entirety.

TECHNICAL FIELD

The present invention relates to implantable medical devices. Moreparticularly, the present invention relates to an inductive elementconfigured to associate with an implantable medical device to reduceMRI-induced currents in the implantable medical device.

BACKGROUND

Magnetic resonance imaging (MRI) is a non-invasive imaging procedurethat utilizes nuclear magnetic resonance techniques to render imageswithin a patient's body. Typically, MRI systems employ the use of amagnetic coil having a magnetic field strength of between about 0.2 to 3Teslas (T). During the procedure, the body tissue is briefly exposed toRF pulses of electromagnetic energy in a plane perpendicular to themagnetic field. The resultant electromagnetic energy from these pulsescan be used to image the body tissue by measuring the relaxationproperties of the excited atomic nuclei in the tissue.

During imaging, the electromagnetic fields produced by the MRI systemmay be picked up by implantable device leads used in implantable medicaldevices such as pacemakers or cardiac defibrillators. This energy may betransferred through the lead to the electrode in contact with thetissue, which may lead to elevated temperatures at the point of contact.The degree of tissue heating is typically related to factors such as thelength of the lead, the conductivity or impedance of the lead, and thesurface area of the lead electrodes. Exposure to a magnetic field mayalso induce an undesired voltage on the lead.

SUMMARY

Discussed herein are various embodiments of an inductive elementconfigured to associate with an implantable medical device lead to makethe implantable medical device lead magnetic resonance (MR) conditional,as well as implantable medical device leads associated with suchinductive elements.

In Example 1, a system includes a medical device lead including aconnector at a proximal end of the lead, a conductor electricallyconnected to the connector at a proximal end of the conductor, and atleast one electrode coupled to a distal end of the conductor. The systemfurther includes a device securable to the proximal end of the leadincluding an inductive element. The device includes a port configured toreceive the connector and position the inductive element around at leasta portion of the connector.

In Example 2, the system according to Example 1, wherein the devicecomprises a lead cap configured to cover the proximal end of the lead.

In Example 3, the system according to Example 2, wherein the lead capincludes a connector block configured to electrically couple the leadcap with the connector on the lead to electrically terminate the lead.

In Example 4, the system according to any of Examples 1-3, wherein thedevice comprises a lead adapter.

In Example 5, the system according to Example 4, wherein the leadadapter further comprises a lead adapter connector configured toelectrically couple with the connector on the lead, and wherein the leadadapter is configured to electrically and mechanically connect the leadto an implantable pulse generator.

In Example 6, the system according to either Example 4 or Example 5,wherein the lead adapter includes a connector block configured toelectrically couple the lead adapter with the connector on the lead.

In Example 7, the system according to any of Examples 1-6, wherein theinductive element comprises a coil, and wherein a winding direction ofthe coil is same as a winding direction of the conductor.

In Example 8, the system according to any of Examples 1-7, wherein theconductor defines a lumen that extends through the lead, and wherein thesystem further comprises an inductive lumen coil positionable within thelumen proximate to the distal end of the conductor.

In Example 9, the system according to any of Examples 1-8, wherein theinductive element comprises one or more filars wound in a plurality ofcoil layers including a first coil layer of the one or more filars woundin a first winding direction, a second coil layer of the one or morefilars coaxial with the first winding and wound in a second windingdirection opposite the first winding direction, and a third coil layerof the one or more filars coaxial with the first and second windings andwound in the first winding direction.

In Example 10, a device for transforming a non-MR conditional lead intoan MRI conditionally safe lead includes an insulative housing includinga port configured to receive a connector of the non-MR conditional lead.The device further includes an inductive element disposed around atleast a portion of the port and positioned within the housing such thatthe inductive element surrounds at least a portion of the connector fromthe non-MR conditional lead when the connector is received in the port.

In Example 11, the device according to Example 10, wherein the device isconfigured as a lead cap for covering the proximal end of the non-MRconditional lead.

In Example 12, the device according to either Example 10 or Example, 11,and further including a connector block configured to electricallycouple the device with the connector on the lead such that the connectorblock electrically terminates the non-MR conditional lead.

In Example 13, the device according to any of Examples 10-12, whereinthe device is configured as a lead adapter configured to electricallyand mechanically connect the non-MR conditional lead to an implantablepulse generator, and wherein the device further comprises a lead adapterconnector configured to electrically couple with the connector of thenon-MR conditional lead.

In Example 14, the device according to Example 13, and furthercomprising a connector block configured to electrically couple thedevice with the connector on the non-MR conditional lead.

In Example 15, the device according to any of Examples 10-14, whereinthe inductive element comprises a coil, and wherein a winding directionof the coil is the same as the winding direction of a conductor in thenon-MR conditional lead.

In Example 16, the device according to any of Examples 10-15, whereinthe inductive element comprises one or more filars wound in a pluralityof coil layers, a first coil layer of the one or more filars wound in afirst winding direction, a second coil layer of the one or more filarscoaxial with the first winding and wound in a second winding directionopposite the first winding direction, and a third coil layer of the oneor more filars coaxial with the first and second windings and wound inthe first winding direction.

In Example 17, a lead assembly includes a non-MR conditional medicaldevice lead including a connector at a proximal end of the lead, aconductor electrically connected to the connector at a proximal end ofthe conductor, and at least one electrode coupled to a distal end of theconductor. The lead assembly further comprises an inductive elementsecured to the proximal end of the lead and comprising a coil. Theinductive element includes a port that receives the connector andpositions the coil around at least a portion of the connector.

In Example 18, the lead assembly according to Example 17, wherein thedevice comprises a lead cap that covers the proximal end of the non-MRconditional medical device lead.

In Example 19, the lead assembly according to Example 17, wherein thedevice comprises a lead adapter, and wherein the lead adapter furthercomprises a lead adapter connector electrically coupled with theconnector on the non-MR conditional medical device lead, and wherein thelead adapter is configured to electrically and mechanically connect theelectrically coupled lead to an implantable pulse generator.

In Example 20, the lead assembly according to any of Examples 17-19,wherein the inductive element comprises a coil, and wherein a windingdirection of the coil is the same as a winding direction of theconductor.

While multiple embodiments are disclosed, still other embodiments of thepresent invention will become apparent to those skilled in the art fromthe following detailed description, which shows and describesillustrative embodiments of the invention. Accordingly, the drawings anddetailed description are to be regarded as illustrative in nature andnot restrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a system illustrating various embodimentsof an inductive element for providing MRI compatibility in animplantable medical device lead.

FIG. 2 is a schematic view of an embodiment of a lead cap including aninductive element.

FIG. 3 is a schematic view of an embodiment of a lead adapter includingan inductive element.

FIG. 4 is a schematic view of a proximal end of a lead illustrating anembodiment of an inductive coil insertable in an inner lumen of thelead.

FIG. 5 is a perspective view of an embodiment of a high inductance coilaccording to embodiments of the present disclosure.

While the invention is amenable to various modifications and alternativeforms, specific embodiments have been shown by way of example in thedrawings and are described in detail below. The intention, however, isnot to limit the invention to the particular embodiments described. Onthe contrary, the invention is intended to cover all modifications,equivalents, and alternatives falling within the scope of the inventionas defined by the appended claims.

DETAILED DESCRIPTION

FIG. 1 is a schematic view of a system 100 including an implantablemedical device (IMD) 102. As is shown, the IMD 102 is disposed in thevicinity of a magnetic resonance imaging (MRI) system 104. The IMD 102includes a pulse generator 106 and one or more leads 110 deployed in apatient's heart H. For purposes of illustration, FIG. 1 shows threeleads, referred to as leads 110 a, 110 b, and 110 c, implanted invarious chambers of the heart H. The lead 110 a is an abandoned lead,and the leads 110 b and 110 c are active leads coupled to the pulsegenerator 106.

The pulse generator 106 is typically implanted subcutaneously within animplantation location or pocket in the patient's chest or abdomen. Thepulse generator 106 may be any implantable medical device, known in theart or later developed, for delivering an electrical therapeuticstimulus to the patient. In various embodiments, the pulse generator 106is a pacemaker, an implantable cardiac defibrillator, and/or includesboth pacing and defibrillation capabilities. Any excess lead length,i.e., length beyond that needed to reach from the location of the pulsegenerator 106 to the desired intracardiac implantation site, isgenerally coiled up in the subcutaneous pocket near the pulse generator106.

Each of the leads 110 a-110 c includes a distal end 112 and a proximalend 114 (shown only on lead 110 c for ease of illustration). Each of theleads 110 a-110 c includes a connector 116 at the proximal end 114. Aconductor 118 extends through the lead body of each of the leads 110a-110 c, and is coupled to the connector 116 at the proximal end 114 andto one or more electrodes 120 at the distal end 112. For ease ofillustration, the connector 116, conductor 118, and electrode 120 arelabeled only on lead 110 c, but leads 110 a and 110 b can includesimilarly configured and located elements. It is noted that while oneconductor 118 is shown, more than one conductor can be providedextending within each lead body.

In some embodiments, the conductor 118 is covered by an outer insulatinglayer that forms the lead body. In some embodiments, the conductor 118defines a conductor lumen 132 that extends through the lead 110 (e.g.,lead 110 c) from the proximal end 114 to the distal end 112 of the lead110.

The connector 116 couples each of the leads 110 b and 110 c to the pulsegenerator 106 to electrically connect the one or more electrodes 120 onthe leads 110 b, 110 c to the pulse generator 106 via the conductor 118.As shown, the connector 116 of the lead 110 a is configured forconnection to the pulse generator 106, but is disconnected. A lead(e.g., lead 110 a) that is not connected to a pulse generator 106 andsubsequently left in the heart H is termed an “abandoned lead.”

As shown in FIG. 1, the leads 110 b and 110 c operate to conveyelectrical signals and stimuli between the heart H and the pulsegenerator 106. For example, in the illustrated embodiment, the lead 110a is implanted in the right atrium, the lead 110 b is implanted in theleft ventricle, and the lead 110 c is implanted into the rightventricle. As shown, the leads 110 a-110 c enter the vascular systemthrough a vascular entry site formed in the wall of a left subclavianvein, extending through a brachiocephalic vein and a superior vena cava.In other embodiments, the leads 110 a-110 c may enter the vascularsystem through a right subclavian vein, a left axillary vein, a leftexternal jugular, an internal jugular, or a left brachiocephalic vein.The electrical signals and stimuli conveyed by the pulse generator 106are carried to the electrode 120 at the distal end 112 of the leads 110b, 110 c by the conductor 118.

In an MRI environment, as shown in FIG. 1, the electromagnetic radiationproduced by the MRI system 104 may be picked up by the conductor 118 ofeach of the leads 110 a-110 c, regardless of whether the leads 110 a-110c are connected to the pulse generator 106. The electromagnetic energyis transferred through the leads 110 a-110 c to the electrode 120 incontact with the target tissue, which may lead to elevated temperaturesat the point of contact.

The devices as described in further detail herein include inductiveelements (e.g., inductive coils) and are configured to associate withnon-MR conditional leads to transform the leads into MR conditionalleads. An MR conditional device poses no known hazards in a specifiedMRI environment with specified conditions of use. In some embodiments, adevice to transform a non-MR conditional lead into an MR conditionallead can include, for example, a lead cap 140 including an inductiveelement secured to the proximal end 114 of the lead, as shown attachedto the lead 110 a. An embodiment of the lead cap 140 according to thepresent disclosure is described below with regard to FIG. 2. A secondexample device to transform a non-MR conditional lead into an MRconditional lead can include a lead adapter 142 including an inductiveelement is secured to the proximal end 114 of the lead, as shown coupledto the proximal end of the lead 110 b. An embodiment of the lead adapter142 according to the present disclosure is described herein with regardto FIG. 3. A third example device can include an inductive coil 144 ispositioned near the distal end 112 of the lead in the conductor lumen132, as shown at the distal end of the lead 110 c. An embodiment of theinductive coil 144 according to the present disclosure is describedherein with regard to FIG. 4.

FIG. 2 is a schematic illustration of a lead cap 140 configured tocouple to the connector 116 at the proximal end 114 of the lead 110 a(FIG. 1). The lead cap 140 has a distal end portion 204 and a proximalend portion 206. The lead cap 140 includes an insulative housing 208, aport 210, and an inductive element 212. The insulative housing 208extends from the distal end portion 204 to the proximal end portion 206.The insulative housing 208 can include an outer wall 214 and an innerwall 216 and a lumen 218 defined within the inner wall 216 and extendingfrom the proximal end portion 206 to the distal end portion 204 of thehousing 208. The port 210 provides an opening to the lumen 218 at thedistal end portion 204. The port 210 and lumen 218 are configured toreceive and retain the connector 116. The inductive element 212 can bedisposed around at least a portion of the port 210 and positioned withinthe housing 208 such that the inductive element 212 surrounds at least aportion of the connector 116 from the non-MR conditional lead when theconnector is received in the lumen 218. In some embodiments, theinductive element 212 can be a high inductance coil.

In some embodiments, the housing 208 can be formed of a polymer. In someembodiments, the housing 208 is formed of a polymeric biocompatiblematerial. Exemplary materials that may be used for the housing 208 isinclude, but are not limited to, expanded polytetrafluoroethylene(ePTFE), layered ePTFE, polytetrafluoroethylene (PTFE), polyethyleneterephthalate (PETE), ethylene/tetrafluoroethylene copolymer (ETFE),fluorinated ethylene propylene (FEP), polyether ether ketone (PEEK),polyamides, polyimides, para-aramid synthetic fibers, and polyurethane,among other materials.

The lead cap 140 couples with the connector 116 of the lead 110 a toelectrically terminate the lead 110 a. In some embodiments, such as in aunipolar lead, the lead cap 140 further includes a connector block 226.The connector block 226 can be electrically coupled to the inductiveelement 212. The connector block 226 is positioned around the lumen 218within the housing 208 such that the connector block 226 is electricallyconnectable to a connector 116 disposed within the lumen 218. In someembodiments, the connector block 226 is mechanically and electricallycouplable to the connector 116 using a fixation mechanism (not shown),such as one or more set screws. Thus, the connector block 226 operatesto electrically couple the inductive element 212 to the connector 116.In other embodiments, the lead cap 140 may not include the connectorblock 226, which results in the inductive element 212 not beingelectrically connected to the connector 116. In such embodiments, theinductive element 212 “floats” over the connector 116.

In the illustrated embodiment, the inductive element 212 can include asingle filar 230 that is helically wound with a plurality of turnsaround a longitudinal axis A of the lumen 218 in a particular windingdirection W, for example, a left-handed (LH) winding direction. In someembodiments, the inductive element 212 can include two or more filars(see, e.g., FIG. 5). The inductive element 212 can also have a coilpitch, defined as a length from the center of a turn of a wire of theinductive element 212 to the center of an adjacent turn of the wire ofthe inductive element 212, of between about one and two times thediameter of the filar 230.

The inductance of the inductive element 212 can be determined, in part,by its geometric properties, including whether the inductive element 212is straight or coiled. For a coiled or wound inductive element 212,several parameters influence its inductance, including the coil pitch,the outer diameter, the cross-sectional area of the inductive element212, and the number of filars 230 in the inductive element 212. Thus,the dimensions and characteristics of the inductive element 212 may beselected to minimize the effects of MRI fields on the performance andresponse of the lead 110 a.

In some embodiments, the inductive element 212 is wound in the samedirection W as the conductor 118 in the lead 110 a. For example, if theconductor 118 is coiled in the LH winding direction, then the inductiveelement 212 can also be coiled in the same LH winding direction. Theinductive element 212 has a higher inductance than the conductor 118, sothe overall inductance of the lead 110 a is increased by coupling theinductive element 212 to the conductor 118. As a result, the amount ofMRI induced current on the conductor 118 is reduced.

In operation, the lead cap 140 can be placed over the proximal end 114of the lead 110 a. The port 210 receives the connector 116 of the lead110 a, which traverses through the lumen 218 to the proximal end 206 ofthe lead cap 140 until the inductive element 212 is disposed around atleast a portion of the connector 116. By surrounding at least a portionof the connector 116 with the inductive element 212, the overallinductance of the lead 110 a is increased, thereby reducing the amountof MRI-induced current that is picked up and transmitted by theconductor 118. As a result, the inductive element 212 prevents orreduces temperature increase at the one or more electrodes 120.

FIG. 3 is a schematic illustration of a lead adapter 142 configured tocouple to and cover the connector 116 at the proximal end 114 of thelead 110 b (FIG. 1). The lead adapter 142 has a distal end portion 304,a proximal end portion 306, and an intermediate portion 308. The leadadapter 142 can include an insulative housing 310, a port 312, a leadadapter connector 314, and an inductive element 315. The insulativehousing 310 extends from the distal end portion 304 to the intermediateportion 308. The insulative housing 310 includes an outer wall 316, aninner wall 318, and a lumen 320 defined within the inner wall 318 andextending from a proximal end portion 322 to a distal end portion 324 ofthe housing 310. The port 312 provides an opening to the lumen 320 atthe distal end portion 304 of the lead adapter 142. The port 312 andlumen 320 are configured to receive and retain the connector 116 on thelead 110 b. The inductive element 315 can be disposed around at least aportion of the port 312 and positioned within the housing 310 such thatthe inductive element 315 surrounds at least a portion of the connector116 from the non-MR conditional lead when the connector 116 is receivedin the lumen 320. In some embodiments, the inductive element 315 is ahigh inductance coil.

In some embodiments, the housing 310 can be formed of a polymer. In someembodiments, the housing 310 is formed of a polymeric biocompatiblematerial. Exemplary materials that may be used for the housing 310 isinclude, but are not limited to, expanded ePTFE, layered ePTFE, PTFE,PETE, ETFE, FEP, PEEK, polyamides, polyimides, para-aramid syntheticfibers, polyurethane, and silicone, among others.

In some embodiments, such as when the lead adapter 142 is used inassociation with a unipolar lead, the lead adapter 142 can furtherinclude a connector block 332. The connector block 332 can beelectrically coupled to the inductive element 315. The connector block332 is positioned around the lumen 320 within the housing 310 such thatthe connector block 332 is electrically connectable to a connector 116disposed within the lumen 320. In some embodiments, the connector block332 is mechanically and electrically couplable to the connector 116using a fixation mechanism (not shown), such as one or more set screws.Thus, the connector block 332 operates to electrically couple theinductive element 315 to the connector 116. In other embodiments, thelead adapter 142 may not include the connector block 332, which resultsin the inductive element 315 not being electrically connected to theconnector 116. In such embodiments, the inductive element 315 “floats”over the connector 116.

In the illustrated embodiment, the inductive element 315 can include asingle filar 340 that is helically wound with a plurality of turnsaround a longitudinal axis of the lumen 320 in a particular windingdirection, for example, a left-handed (LH) winding direction. In otherembodiments, the inductive element 315 includes two or more filars (see,e.g., FIG. 5). The inductive element 315 can also have a coil pitch ofbetween about one and two times the diameter of the filar 340.

The inductance of the inductive element 315 is determined, in part, byits geometric properties, including whether the inductive element 315 isstraight or coiled. For a coiled, or wound, inductive element 315several parameters influence its inductance including: coil pitch, outerdiameter, cross-sectional area of the inductive element 315, and numberof filars 340 in the inductive element 315. Thus, the dimensions andcharacteristics of the inductive element 315 may be selected to minimizethe effects of MRI fields on the performance and response of the lead110 b.

In some embodiments, the inductive element 315 can be wound in the samedirection as the conductor 118 in the lead 110 b. For example, if theconductor 118 is coiled in the LH winding direction, then the inductiveelement 315 can also be coiled in the same LH winding direction. Theinductive element 315 can be configured to increase the overallinductance of the lead 110 b to reduce the amount of MRI inducedcurrents on the conductor 118.

In operation, the lead adapter 142 can be placed over the proximal end114 of the lead 110 b. The port 312 receives the connector 116 of thelead 110 b, which traverses through the lumen 320 to the proximal endportion 322 of the housing 310 until the inductive element 315 isdisposed around at least a portion of the connector 116. The leadadapter connector 314 is then coupled to the pulse generator 106. Bysurrounding at least a portion of the connector 116 with the inductiveelement 315, the overall inductance of the lead 110 b is increased,thereby reducing the amount of MRI-induced current that is picked up andtransmitted by the conductor 118. As a result, the inductive element 315prevents or reduces temperature increase at the one or more electrodes120, and can prevent or reduce the amount of current injected into thepulse generator 106.

FIG. 4 is a schematic illustration of a portion of the lead 110 c withan embodiment of the inductive element 144 being inserted into theproximal end of the connector 116. As discussed herein, and illustratedin FIG. 1, the inductive element 144 can be configured to traversethrough the conductor lumen 132 of the conductor 118 extending throughthe lead 110 c. In some embodiments, the inductive element 144 ispositioned at the distal end portion 112 of the lead 110 c proximate tothe one or more electrodes 120. The inductive element 144 increases theinductance of the conductor 118, thereby reducing the heating of the oneor more electrodes at the distal end 112 of the lead 110 c.

The inductive element 144 can be guided using an insertion tool (notshown) into the lumen 132 of the conductor 118 and moved toward thedistal end portion 112 of the lead 110 c proximate to the electrode 120.The insertion tool used can be a guide wire or a stylet. Other insertiontools can also be used for the purpose of guiding the inductive element144 through the lead 110 c. The inductive element 144 may be a highinductance coil and can include a wire or filar 402 wound into a coilwith an outer diameter 404 smaller than the inner diameter of theconductor 118. The inductive element 144 can serve as a micro conductorfor reducing the MRI field induced heating in the one or more electrodes120. The inductive element 144 may be employed in lieu of or in additionto the lead cap 140 or the lead adapter 142 as discussed herein withrespect to FIGS. 2 and 3, respectively.

FIG. 5 is a perspective view of an inductive element 500, including oneor more filars 502. The inductive element 500 is an alternativeconfiguration to the coiled inductive elements as described herein withregard to FIGS. 2-4. In some embodiments, one or more filars 502 of theinductive element 500 are wound in a plurality of coil layers. Forexample, a first coil layer 510 can be wound in a first windingdirection B1, a second coil layer 512 can be coaxial with the firstwinding and wound in a second winding direction B2 opposite the firstwinding direction, and a third coil layer 514 can be coaxial with thefirst and second windings and wound in the first winding direction B1.The inductive element 500 may be employed for the inductive elementsdescribed herein, including the inductive element 212 in the lead cap140 (FIG. 2), the inductive element 315 in the lead adapter 142 (FIG.3), and the inductive element 144 insertable in the conductor lumen 132(FIG. 4).

In FIG. 5, portions of each of the plurality of coil layers have beenremoved to illustrate each of the underlying layers such as 510 and 512.The filars 502 of the inductive element 500 are co-radially wound alonga direction for example, direction B1 to form the first coil layer 510with a close pitch. The filars 502 are then wound back on themselves inthe reverse direction over and coaxially with the first coil layer 510.The pitch of the second coil layer 512 may be greater than the pitch ofthe first coil layer 512, and winding in reverse direction results inthe formation of second coil layer 512 over the first coil layer 510.The filars 502 are then wound back on themselves again, reversingdirection from the second coil layer 512 (i.e., in the same direction asthe inner first coil layer 510) to form the third coil layer 514 overthe second coil layer 512. The pitch of the third coil layer 514 may besmaller than the pitch of the second coil layer 512.

In some embodiments, the inductive element 500 includes two to fiftyfilars 502. In some embodiments, the diameter of each filar 502 can bein the range of about 0.001 inch to 0.010 inch (0.003-0.025 cm). Thefilars may be composed of a biocompatible material, including, but notlimited to, gold (Au), silver (Ag), Nitinol, titanium (Ti), platinum(Pt), iridium (Ir), a nickel-cobalt base alloy (MP35N), or stainlesssteel. Each of the filars may also include an insulation layer (notshown) of a biocompatible and dielectric material, such as, for example,Teflon, nylon, polymers, PTFE, ETFE, silicone, polyurethane, PEEK,and/or epoxy. The thickness of the insulation layer may be less thanabout 0.005 inch (0.01 cm). In some embodiments, the outside diameter ofthe conductive assembly is less than about 0.10 inch (0.25 cm).

Various modifications and additions can be made to the exemplaryembodiments discussed without departing from the scope of the presentinvention. For example, while the embodiments described above refer tothe particular features, the scope of this invention also includesembodiments having different combinations of features and embodimentsthat do not include all of the described features. Accordingly, thescope of the present invention is intended to embrace all suchalternatives, modifications, and variations as falling within the scopeof the claims, together with all equivalents thereof.

We claim:
 1. A system comprising: a medical device lead including: aconnector at a proximal end of the lead; a conductor electricallyconnected to the connector at a proximal end of the conductor; and atleast one electrode coupled to a distal end of the conductor; and adevice securable to the proximal end of the lead and comprising aninductive element, the device including a port configured to receive theconnector and position the inductive element around at least a portionof the connector.
 2. The system of claim 1, wherein the device comprisesa lead cap configured to cover the proximal end of the lead.
 3. Thesystem of claim 2, wherein the lead cap includes a connector blockconfigured to electrically couple the lead cap with the connector on thelead to electrically terminate the lead.
 4. The system of claim 1,wherein the device comprises a lead adapter.
 5. The system of claim 4,wherein the lead adapter further comprises a lead adapter connectorconfigured to electrically couple with the connector on the lead, andwherein the lead adapter is configured to electrically and mechanicallyconnect the lead to an implantable pulse generator.
 6. The system ofclaim 5, wherein the lead adapter includes a connector block configuredto electrically couple the lead adapter with the connector on the lead.7. The system of claim 1, wherein the inductive element comprises acoil, and wherein a winding direction of the coil is the same as awinding direction of the conductor.
 8. The system of claim 1, whereinthe conductor defines a lumen that extends through the lead, and whereinthe system further comprises: an inductive lumen coil positionablewithin the lumen proximate the distal end of the conductor.
 9. Thesystem of claim 1, wherein the inductive element comprises one or morefilars wound in a plurality of coil layers, a first coil layer of theone or more filars wound in a first winding direction, a second coillayer of the one or more filars coaxial with the first winding and woundin a second winding direction opposite the first winding direction, anda third coil layer of the one or more filars coaxial with the first andsecond windings and wound in the first winding direction.
 10. A devicefor transforming a non-MR conditional lead into an MRI conditionallysafe lead, the device comprising: an insulative housing including a portconfigured to receive a connector of the non-MR conditional lead; and aninductive element disposed around at least a portion of the port andpositioned within the housing such that the inductive element surroundsat least a portion of the connector from the non-MR conditional leadwhen the connector is received in the port.
 11. The device of claim 10,wherein the device is configured as a lead cap for covering the proximalend of the non-MR conditional lead.
 12. The device of claim 11, andfurther comprising: a connector block configured to electrically couplethe device with the connector on the lead such that the connector blockelectrically terminates the non-MR conditional lead.
 13. The device ofclaim 10, wherein the device is configured as a lead adapter, andfurther comprises: a lead adapter connector configured to electricallycouple with the connector of the non-MR conditional lead, and whereinthe lead adapter is configured to electrically and mechanically connectthe non-MR conditional lead to an implantable pulse generator.
 14. Thedevice of claim 13, and further comprising: a connector block configuredto electrically couple the device with the connector on the non-MRconditional lead.
 15. The device of claim 10, wherein the inductiveelement comprises a coil, and wherein a winding direction of the coil isthe same as a winding direction of a conductor in the non-MR conditionallead.
 16. The device of claim 10, wherein the inductive elementcomprises one or more filars wound in a plurality of coil layers, afirst coil layer of the one or more filars wound in a first windingdirection, a second coil layer of the one or more filars coaxial withthe first winding and wound in a second winding direction opposite thefirst winding direction, and a third coil layer of the one or morefilars coaxial with the first and second windings and wound in the firstwinding direction.
 17. A lead assembly comprising: a non-MR conditionalmedical device lead including a connector at a proximal end of the lead,a conductor electrically connected to the connector at a proximal end ofthe conductor, and at least one electrode coupled to a distal end of theconductor; and an inductive element secured to the proximal end of thelead and comprising a coil, the inductive element including a port thatreceives the connector and positions the coil around at least a portionof the connector.
 18. The lead assembly of claim 17, wherein theinductive element comprises a lead cap that covers the proximal end ofthe non-MR conditional medical device lead.
 19. The lead assembly ofclaim 17, wherein the inductive element comprises a lead adapter, andwherein the lead adapter further comprises a lead adapter connectorelectrically coupled with the connector on the non-MR conditionalmedical device lead, and wherein the lead adapter is configured toelectrically and mechanically connect the electrically coupled lead toan implantable pulse generator.
 20. The lead assembly of claim 17,wherein the inductive element comprises a coil, and wherein a windingdirection of the coil is the same as a winding direction of theconductor.